Based on the results of detailed population synthesis models, Girardi et al. (1998) recently claimed that the clump of red giants in the colour–magnitude diagram (CMD) of composite stellar populations should present an extension to lower luminosities, which goes down to about 0.4 mag below the main clump. This feature is made of stars just massive enough for having ignited helium in nondegenera...

We have investigated the influence of the radiation field from a Herbig-Haro object on a spherical clump, as the HH object passes by the clump. We have included a limited chemistry, and show column density maps of HCO+ and NH3 to represent the morphology of the predicted emission regions. The morphology is sensitive both to the orientation of the line of sight with respect to the HH trajectory ...

Mean colors and magnitudes of RR Lyrae stars in 24 fields towards the Galactic bulge from the MACHO database are presented. Accurate mean reddenings are computed for these fields on the basis of the mean colors. The distribution along the line of sight of the RR Lyrae population is examined on the basis of the mean magnitudes, and it is shown that the bulk of the RR Lyrae population is not barr...

We use Subaru Suprime-Cam and VLT FORS1 photometry of the dwarf galaxy DDO210 to study the global stellar content and structural properties of a transitiontype galaxy (with properties intermediate between dwarf irregular and dwarf spheroidal systems). This galaxy is sufficiently isolated that tidal interactions are not likely to have affected its evolution in any way. The colour-magnitude diagr...

The color-magnitude diagrams of ∼ 5 × 10 stars obtained for 13 fields towards the Galactic bulge with the OGLE project reveal a well-defined population of bulge red clump stars. We find that the distributions of the extinction-adjusted apparent magnitudes of the red clump stars in fields lying at l = ±5 in galactic longitude differ by 0.37± 0.025 mag. Assuming that the intrinsic luminosity dist...

Zaritsky and Lin have recently suggested that the color magnitude diagram of the Large Magellanic Cloud (LMC) contains evidence of foreground red clump stars. They interpret this as evidence of tidal debris or a dwarf galaxy at a distance of ∼ 35 kpc which may be responsible for the large gravitational microlensing optical depth observed by the MACHO Collaboration. I derive a relationship betwe...

Mass clumps in gravitational lens galaxies can perturb lensed images in characteristic ways. Strong lens flux ratios have been used to constrain the amount of dark matter substructure in lens galaxies, and various other observables have been considered as additional probes of substructure. We study the general theory of lensing with stochastic substructure in order to understand how lensing obs...

In an effort to understand unusual power-law spectral slopes observed in some hypercompact HII regions, we consider the radio continuum energy distribution from an ensemble of spherical clumps. An analytic expression for the free-free emission from a single spherical clump is derived. The radio continuum slope (with Fν ∝ ν ) is governed by the population of clump optical depths N(τ), such that ...

Conventional methods for management of data-rich fisheries maintain sustainable populations by assuring that lifetime reproduction is adequate for individuals to replace themselves and accounting for density-dependent recruitment. Fishing is not allowed to reduce relative lifetime reproduction, the fraction of current egg production relative to unfished egg production (FLEP), below a sustainabl...